The Natureline purple martin gourd features a vent cap cover which can be closed early in the season to conserve heat, or opened in hot weather to release heat. The snap-in access door eliminates the need to disassemble the gourd for year-end cleaning and allows easy access for monitoring of nestlings.Other features include: OPAQUE WHITE IN COLOR - Aids in the reduction of heat. 11" Diameter - Gives a larger nesting area, reduces heating and allows the nest to be built away from the entrance and the threat of predators. DOOR OPTIONS - "Traditional" 2 inch diameter hole. "Starling Resistant" Oval Hole or Blank Door for use as a winter plug or cut your preferred opening. All doors are completely interchangeable. RAIN CANOPY - Protects the entrance hole. DRAIN HOLES - Two large holes in bottom help keep the inside of the gourd drier. DURABLE - Gourd is made of reprocessed plastic with UV inhibitors added to withstand the effects of the sun. EASILY ASSEMBLED - Four screws require only a screwdriver to assemble.